View Full Version : to extend WLAN range: repeater or high-gain antenna?
04-02-2005, 04:31 PM
Which is a better way to extend the range of a WLAN, a repeater or a high-gain antenna?
We just set up a wireless "g" home network. Our broadband cable comes in to one building (A) where we've installed a LinkSys g wireless router ("w/ SpeedBooster"). We only need to send the signal wirelessly to one other notebook computer (with a "Speedbooster"-compatible card from Broadcom, for whatever that's worth!) which is in another building (B) right next to building A.
Our problem is distance and obstructions. Total distance from the router to where the notebook is being used is between 50 to 75 feet. Building A has brick walls. Building B is woodframe construction with old thick plaster on the walls. Sometimes we have no problem getting the connection and getting on line. Sometimes the signal is too weak to establish the connection - can't obtain a temporary address - and then we have to move the notebook closer until we obtain the address, after which we stay connected, though the internet feed-through is sometimes slow.
So what is the best solution for extending the range/signal-strength?
From what I've read, there are (at least) 2 options: a repeater ( like the Linksys Wireless-G Range Expander [~$90 - $100]), or a high gain antenna [$30-50 and up]. Is this correct? If so,
First question, then: What are the pros and cons of each approach?
Second question: I also have read that there are different kinds of high-gain antennae: omni-directional, like the ones that linksys sells as add-ons to their router (the simplest and cheapest approach, if adequate?), or directional types. The later seems to make more sense to me, since we only need to send the signal in a very specific direction and in a fairly narrow cone shape to cover the entire area we need. Does a directional antenna make more sense for us? And if so, what type would be simplest to install and not too much $$? I've found one on line called a Super Cantenna (www.cantenna.com) which sound simple enough and idiot-proof enough for me, but I don't know if it's junk or not, or if I should go for something better (and more elaborate) if I go the antenna route. And if I need something better than the Super Cantenna, what type? I'm confused by all of the choices: desktop bi-directional antennae, flat wall-mounted types, YAGI (sp?) types, mini-dish-types; yipes!!
One last question: one article about antennae which I found on line said that if I use a high-gain directional antenna, then I'd actually need 2! - one at the router, and another connected to the notebook! Is that true? If so, that would be both expensive and a pain in the rear.
Looking forward to hearing your responces and opinions; thanks!
04-02-2005, 04:42 PM
For your application, I would go with the repeater. It is a stronger solution.
04-02-2005, 05:02 PM
Thanks for your opinion. If I go this route, does the repeater need to be receiving a strong signal, or can it amplify a weak signal? In other words,
Where would be the best place to try putting it: at the farthest point in building A, or at the nearest point in building B - where the signal is already weak?
Wireless router > 25' > brick wall (end of building A)> outdoors (20') > Building B (wood and plaster wall) > 10' - 30' range where notebook is used.
04-02-2005, 06:19 PM
You want to repeat a strong signal. I would try to put as close to a window near the router.
04-02-2005, 07:22 PM
Thanks. Still haven't totally decided on the repeater vs. high-gain antenna question, but your input will be helpful. I appreciate it.
04-02-2005, 09:14 PM
I would think a repeater will give a stronger link than the high gain antenna solution particularly for bidirectional communication.
Just an opinion.
04-03-2005, 12:34 AM
Thanks. All opinions welcome and appreciated! The more the better.
04-03-2005, 05:22 PM
Your best bet is to go with a repeater. Whoever said that you will need two high-gains was correct, and this option would end up being more labor-intensive and more expensive.
Also, I'm not sure if it's possible with your situation, but you could put the router in the window of Building A and put the repeater at the nearest point in Building B (also being near a window would help tremendously. I'm not sure if your router has two antennas, but if so, you can get maximum range out of it by keeping one of them completely vertical and the other parallel to the ground.
Lastly, Building-to-building wireless will definitely call for you to use some sort of good encryption (WPA). Just a thought for when you get this thing up and running.
04-03-2005, 07:53 PM
Hmm... So far, three votes for repeater, Zero for high-gain antenna. Seems like a consensus developing.
Unfortunately, I can't position the router near a window. But I will try your suggestion about the two antennae positioning. Thanks!
04-03-2005, 11:14 PM
In this situation, there is one best answer: Repeater.
RF signal power "free space" loss occurs as a function of the square of the distance from the transmitter. The simplest solution is to move the transmitter closer to the receiver, the receiver closer to the transmitter, or use a repeater (surrogate RT).
Loss = r squared * (4 pi)squared/lamda squared
In that equation, the only variable you control is r (range). You control it by moving the Tx or Rx or using an intermediate RT.
Unless of course you change lamda, which is the wavelength, which is inversely proportional to the frequency at which you are transmitting. But you won't be changing lamda. Your frequency will be fixed, most likely at 2.4GHz.
The free space loss equation does not take into account loss induced by attenuation (walls/floors) or scattering (reflection/multipath/fading). Attenuation alone, due to walls or floors, can account for 10 to 27 dB of signal loss. This is very significant because every 3dB is a factor of 2 (1/2) and every 10dB is an order of magnitude. Scattering further complicates the situation.
This is kind of an over-simplification but it's sort of one of the reasons we don't walk around with giant high gain antennas on our cell phones. Microwave towers, which are repeaters, save us from that.
04-04-2005, 01:30 AM
I do get the message about repeaters over antennae, and please excuse me if I am just being dense with this next question, but your response - what I understand of it - raises another question in my mind.
How can I tell whether my poor signal is a result of distance or of attenuation? I am after all trying to go through a brick wall plus others of wood and plaster. And if it turned out that attenuation caused by these obstructions was my problem, then wouldn't I help the situation most by putting an antenna on the outside of building A (the brick one which houses the router) with a clear line of site to building B?
04-04-2005, 02:06 AM
Classic was pointing out a window location with line of sight is preferred for the first router, with less obstacles in the way of the signal.
04-04-2005, 02:21 AM
How can I tell whether my poor signal is a result of distance or of attenuation?
I don't mean to be coy, but based on what you have described it will be both. And really, the end result is the same--signal loss.
And if it turned out that attenuation caused by these obstructions was my problem, then wouldn't I help the situation most by putting an antenna on the outside of building A (the brick one which houses the router) with a clear line of site to building B?
If I understand you, and you mean an external antenna connected to the router via some kind of extension cable, I guess you could do that. You might have to manufacture the cable yourself if there are no local shops that have them. The kicker might be the type of connector(s) on the router. I think there are two types but I don't remember what they are. Then you would have to mount/secure it and probably provide it with some sort of protection from the elements.
As has been stated by Classic and PrntRhd, the best solution is clear line of site, whether you opt for a high gain antenna OR a repeater.
Heck, you sound inclined toward the antenna idea so go buy one that fits the Linksys, hook it up, make sure the router is near a window facing the other building, and see how it works. If it doesn't, take it back, buy a repeater, and repeat the process. Depending on that result, you can look into the outside antenna idea, which might work best but might also be the most work.
Finally, like FastLearner said, keep in mind that your signal is out there for the neighborhood to use if not encrypted no matter what solution you end up with.
04-04-2005, 03:02 PM
My Plan is this: First thing I'm going to try, as per all of your suggestions, is some re-wiring in "building A" - in order to bring the cable modem and router to a window nearest "building B" - that is, as long as having a 30' cable running from the router to the wired computer won't be a problem?? Is it all right for me to have a long cable like that connecting the router and the wired computer?
(Sorry if that's a dumb question, but I have no experience with these things at all.)
Then I'll see how my connection is after doing that. If neccesary, then I'll try putting a repeater inside of a clear line of sight window in building B - about 20' or 30' away.
I'm guessing that by that point, I should have a good connection. I'll save high-gain antennae for the last option after implementing the first one or two.
(As per everyone's security warnings: thanks. I've enabled all of the router's and WinXP's network security options, as far as I can tell - I'm using their recommended encryption and a good password; question: should I also disable SSID broadcasting [at least I think that's how the option was described - dis-allowing other people to see the SSID]. And I live pretty much out in the woods, so I don't think our signal will be reaching many neighbors or drive-by snoops anyway.)
It may take me till next weekend to do the re-wiring; once I have, I'll report back here on my success (hopefully), or lack thereof, for anyone else wondering about this question.
(A quick OK or not OK regarding the 30' of wired networking cable from someone will be greatly appreciated; thanks!)
04-04-2005, 11:12 PM
You can use runs of Cat 5 cable up to 100 meters max length from the router, so 30 feet will be no sweat.
No problem there.
04-05-2005, 12:12 AM
You got the answer on the cable. I've run as much as 50 feet myself with no problem at all. As for disabling SSID broadcast, as long as you have good encryption enabled, and given where you live, it really isn't necessary.
04-09-2005, 12:32 AM
A final idea. If you have the ability to wire to an antenna to get outside, pull one of the existing antennas off your router, mount it outside and run a wire to that. As far as the signal going through the wood frame/plaster, this should not slow you down too much.
Another solution is to take a look HERE (nocat.net). These guys are local to me and I have been following their antics for a while :D Be sure to check out the "Pringles can" antennas :eek:
04-11-2005, 12:07 PM
Thanks bassman. From the new router location, I may be able to do that easily. Can I just mount one of the existing LinkSys antennas from the router outdoors - I mean, will it hold up to the elements?
Sorry to say but I don't have the progress report I promised yet - for anyone who might have been interested. Talk about "sh*t happens", this is what they mean: our septic tank (out here in the woods we still use those things) collapsed, so instead of re-wiring this weekend, we had to install a new one. Now we have a big new pot to p*ss in, a yardful of new grass seed waiting to sprout, and a Radio Shack bag full of cables for our WLAN waiting until next weekend. I will report back when it's done!
04-18-2005, 01:13 PM
I moved the router so it is next to the window closest to the second building. This provided a definite improvement in signal strenth. The signal now is still not "strong", but it may well turn out to be adequate for our needs. (Based on the "Network Stumbler" software, the signal strength has improved from the high seventies/low eighties - which made aquiring a network connection difficult - to its present solid 69. At this strength we can obtain a connection every time, although I'm expecting that file transfers may be slow. Internet transfer rates seem OK.
We'll see how this works for us for a while; it may be "good enough" the way it is. If I eventually feel compelled to improve the signal more, I'll try some of the other steps suggested to get more incremental gains. Depending on what if anything we feel that we need in terms or further improvement, we could then go with an antenna upgrade (35 - 50 $US) or the probably superior solution of a repeater in the second building (probably around $100).
Thank you all for your advise. I know that the original "repeater vs. high-gain antenna" question hasn't been resolved by my experience, but I hope that this discussion will prove useful nonetheless to others who may be wondering about the same question.
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